This invention relates to apparatus for linearly adjusting the position of devices, and more particularly to such apparatus for adjusting focus of an image generated by an optical character recognition (OCR) read head. The apparatus includes a mechanism for adjusting position of a lens assembly along its optical axis for focusing the lens image at an image plane, and a mechanism for adjustably supporting an image scanning device for receiving the focused image.
In many optical systems for generating and receiving an image, the degree of focus of the received image is critical for its optimum utilization. For example, in OCR systems of the type employing an optoelectronic device situated in the image plane, the output signal generated from the image is enhanced with the degree of image focus. Such systems typically include a read head having a lens assembly positioned for viewing optical characters situated in an object plane, for generating images of such characters at the read head's image plane. Apparatus for supporting the read head with respect to the object plane are not part of the present invention, and such apparatus is disclosed in applicant's copending U.S. patent application Ser. No. 712,014.
The optoelectronic device of this type of read head may comprise a solid state image sensor device or scanning array, with its light sensitive surface optimally situated in the image plane of the lens assembly. The focus of the image on the light sensitive surface may be adjusted by displacing the lens assembly along its optical axis, as well as by displacing the array along the optical axis such that its light sensitive surface is at the plane of the focused image. Such adjustments are desirable when initially setting up the OCR system, and subsequently to compensate for minor shifts of the object plane with respect to the OCR read head.